Combined lightning arrester and fuse cutout



E. L. SANKEY COMBINED LIGHTNING ARRESTER AND FUSE CUTOUT 3 SheetsSheet lINVENTOR.

Edward L 56277 fitter/7y Nov. 16, 1965 Filed Sept. 14, 1962 Nov. 16,1965 E. L. SANKEY COMBINED LIGHTNING ARRESTER AND FUSE CUTOUT 3Sheets-Sheet 2 Filed Sept. 14, 1962 INVENTOR. Edward L. San/ 25y BY 1Nov. 16, 1965 E. L. SANKEY 3,218,517

COMBINED LIGHTNING ARRESTER AND FUSE CUTOUT Filed Sept. 14, 1962 3Sheets-Sheet 5 INVENTOR. Ida/am L. San/K BY flaw M United States PatentM 3,218,517 COMBINED LIGHTNING ARRESTER AND FUSE CUTOUT Edward L.Sankey, Oak Creek, Wis., assignor to McGraw- Edison Company, Milwaukee,Wis., a corporation of Delaware Filed Sept. 14, 1962, Ser. No. 223,69714 Claims. (Cl. 317-66) This invention relates to protective devices forelectrical apparatus and in particular to a combined lighting arresterand fuse cutout construction.

Distribution transformers are conventionally protected by a fuse forclearing transformer faults and a lightning arrester for by-passingimpulse voltages on the line to ground. Usually both a fuse cutout and alightning arrester are mounted on a pole or a crossarm, or one of theprotective devices may be mounted directly on the transformer. In all ofthese mounting arrangements only limited space is available forsupporting the protective devices.

Combination lightning arrester and fuse assemblies are known, butheretofore they either have been impracticable or commerciallyunsuccessful. For example, one known arrester and fuse assembly utilizesan open link fuse cutout Whose interrupting rating is too low for use onmost distribution systems. Further, in this known fuse and arrestercombination the arrester is almost twice as long as the fuse. thusnecessitating that the ground terminal be at the lower end of theinsulating member and that the assembly be mounted at such lower end.The use of an expulsion fuseholder mounted between the upper terminaland an intermediate terminal is impracticable with such arrangementsince manual operation of the fuseholder, which normally is closed by alineman with considerable speed and force, would impose high cantileverstress on the base mounting. Further, the recoil forces resulting fromoperation of an expulsion fuse tube would be transmitted to the basemounting bracket through the relatively weak tubular portion of theporcelain housing. Still further, the known arrester and fusecombinations are not bird-proof and have no means to isolate thearrester and prevent fiow of follow current through the arrester in theevent of damage to the arrester.

It is an object of the invention to provide a combined lightningarrester and fuse tube cutout which saves mounting space on the pole orcrossarm in comparison to separate cutout and arrester; which is lessexpensive to install than sepa-rate cutout and arrester; which hashigher interrupting capacity than known arrester and fuse combinationsthat utilize an open link fuse cutout; which is bird-proof andanimal-proof and thus assures continuity of service to customers andeliminates false outages; which transmits recoil forces, incident tooperation of the fuse tube cutout, to the mounting bracket through ahigh strength portion of the porcelain insulator which may be solid incross section rather than through a weak tubular portion of theporcelain as in prior art devices; which avoids the high cantileverforces which were applied to the base mounting of prior art apparatuswhen the cutout was manually closed; and which has means to isolate thelightning arrester, and thus prevent flow of follow currenttherethrough, in the event of damage to the lightning arrester.

A further object of one embodiment of the invention is to provide acombined lightning arrester and fuse tube cutout which positivelyisolates the lightning arrester in the event of damage to the arresterand also gives a visible indication of arrester damage, thus positivelypreventing line lockout and customer outages.

These and other objects and advantages of the inven- 3,218,517 patentedNov. 16, 1965 ice tion will be more readily apparent from the followingdetailed description when taken in conjunction with the accompanyingdrawing wherein:

FIG. 1 is an elevational view of a preferred embodiment of the inventionmounted on a crossarm;

FIG. 2 is a partial vertical section view through the embodiment of FIG.1 and FIG. 3 is a view similar to FIG. 2 through an alternativeembodiment of the invention.

Referring to FIG. 1 of the drawing, the combined lightning arrester andfuse cutout includes an elongated member of insulating material,preferably high strength, wet-process porcelain, having a metallicmounting hanger 11 affixed thereto intermediate its ends. The metallicmounting hanger 11 is adapted to be connected to ground over a groundwire 12 secured to a terminal 14 mounted on hanger 11. The metallichanger 11 is illustrated as secured to a bracket 15 afiixed to a polecrossarm 16 so as to permit swivelling the hanger 11 and insulatingmember 19 to any desired angle relative to the cross arm 16 and lockingsuch position, but it will be appreciated that the hanger 11alternatively permits mounting directly on a pole, on a transformercasing, or a steel structure as desired.

The portion 17 of the porcelain insulating member 11) above the hanger11 is tubular (see FIG. 2) and houses the lightning arrester assembly 18including valve material 19 and spark gap means 20. The valve material19 preferably comprises a plurality of superimposed valve blocks 21 eachof which has a suitable negative resistance granular material such assilicon carbide molded with an inorganic binder such as sodium silicate.However, it will be appreciated that the valve material may, if desired,be molded directly within the tubular portion 17 of the porcelaininsualting member 10. The spark gap assembly is preferably of the typedisclosed in US. Patent 2,891,193 to F. V. Cunningham, having the sameassignee as the present application, and includes late-rally spacedsupport members 23 preferably of ceramic insulating material havingslots 24 at vertically spaced apart intervals on opposed sides of eachsupport member 23 which receive conductive baffle plates 25. The battleplates 25 are notched at opposed sides to provide shoulder portions (notshown) engageable with the slots 24 of the support members 23. Eachbaffle plate 25 has a central aperture in which an electrode member 26is seated and protrudes from both sides thereof. The upper portion ofthe spark gap assembly 20 is held together by means of a transverseretainer plate 27 having downwardly formed ears 28 embracing the sidesof the opposed support members 23. A depending upper electrode 29 may beformed in the central portion of the retainer plate 27. The bottom valveblock 21 may rest upon a cup-shaped metallic disk 30 spot-welded to theretainer plate 27. An annular insulating member 31 of flexible materialsuch as rubber and of larger diameter than the retainer plate 27 anddisk 30 may be clamped between these members and hold the upper end ofthe spark gap assembly 20 centrally of the tubular portion 17 asdisclosed and claimed in the copending application of Stanley S.Kershaw, Serial No. 82,517, filed January 13, 1961, now Patent Number3,184,634, and having the same assignee as this application. Theinsulating member 31 is in sealing relation with the internal wall oftubular portion 17 to prevent ionized gases formed in the spark gapmeans 20 from drifting in between the valve blocks 21 and the tubularportion 17 where they could form a conductive path around the valveblocks 21. The member 31 also prevents moisture given off by the valveblocks 21 during arrester operation from entering the 3 area of thespark gap means where it could lower the power frequency sparkover ofthe spark gap means 20.

The lower end of the opposed support members 23 are urged together byupwardly extending ears 32 on the lower electrode plate 33 which is spotwelded to a circular metallic member 34 of inverted cup-shape. A lowergap electrode 35 has a depending tubular portion 36 of reduced diameterextending through clearance apertures in lower electrode plate 33 andcup-shape member 34. The tubular portion 36 is spun over to aflixelectrode 35 to lower electrode plate 33 and to also retain an outwardlybiased leaf spring 37 which urges the support members 23 outwardlyagainst the upwardly bent ears 32 on the lower electrode plate 33 toprovide a frictionally held assembly. The inverted cup-shaped member 34of the spark gap assembly 20 is supported upon a metallic disk 38 whichrests upon an annular bone-fibre cushion 39 at the bottom of the axialbore in insulating member 10.

The hanger strap 11 extends into a transverse slot 40 in insulatingmember 10 and is fastened therein by suitable cement 41. A knurledmetallic member 44 has a drive fit within an aperture in hanger 11 andalso has a tapped axial hole 45 in the upper face thereof. A flat headscrew 47 extends through a clearance aperture in disk 38 and through anaxial bore 48 of reduced diameter in insulating member 10 at the bottomof tubular portion 17 and is threaded within tapped hole 45 to provideelectrical connection between the bottom electrode of the spark gapassembly and hanger strap 11. A gasket 49 of flexible materialcompressed between member 54 and the upper surface of transverse slot 40hermetically seals the lower end of tubular portion 17.

A metallic sealing cap 50 is spun over a circumferential flange 51 atthe upper end of insulating member 10 to close the open end of tubularportion 17. A gasket 52 of flexible material compressed between the openend of insulating member 10 and cap 50 hermetically seals the upper endof tubular portion 17. Insulating means 53 such as a sprayed coating ofa suitable epoxy resin or an annular rubber sleeve of generally U-shapedcross section may cover the side and top surfaces of sealing cap 50. Astainless steel coil spring 54 compressed between sealing cap 50 and theupper valve block 21 retains the lightning arrester components inposition within tubular portion 17. Copper straps 55 interconnecting theupper and lower turns of spring 54 shunt the inductance of the springand provide positive electrical connection between the cap 50 and theuppermost valve block 21. The head of a threaded stud 57 passing throughan axial aperture in cap 50 is brazed to cap 50. Stud 57 forms the upperterminal for the lightning arrester, and a flexible metallic connectingstrap 58 is aflixed to stud 57 by a nut 59.

Insulating member 10 at its lower end carries a bottom contact andterminal assembly 61 (hereinafter referred to as the bottom contact)provided with an eyebolt connector 62 which constitutes the loadterminal for the combined fuse and arrester and is adapted to beconnected to a lead 63 from the load. Insulating member also carriesbetween the metallic hanger 11 and the upper terminal 57 an intermediatecontact and terminal assembly 65 (hereinafter referred to as theintermediate contact). An expulsion fuseholder 66 is pivotally mountedon the bottom contact 61 for swinging movement relative to theintermediate contact 65 and is latched to the intermediate contact 65.Fuseholder 66 includes an expulsion fuse tube 68 surrounding a fuse link69. The upper end of fuse tube 68 is aflixed within a tubular, metallic,fuseholder upper contact 70 which is open and threaded at its upper end.A button cap 72 (see FIG. 2) on the end of fuse link 69 is disposedagainst the open end of upper fuse holder contact 70 and is held inplace by an expendable cap 73 threaded onto the end of upper fuseholdercontact 70 and having a frangible section adapted to rupture as theresult of excessive pressure generated within fuse tube 63 when fuselink 69 operates. A hook- Cir stick receiving eye 75 integral with theupper fuseholder contact 70 permits pivoting the fuseholder 66 on thebottom contact 61 and removing the fuseholder 66 from the insulatingmember 10. A laterally extending metallic contact rod 76 is alsointegral with the upper fuseholder contact 70.

The intermediate contact 65 includes a stationary contact supportinghood 77 clamped to insulating member 10 by a U-bolt 79 and a spring 80provided with a shouldered portion 81 behind which the contact rod 76 onthe upper fuseholder contact 70 is positioned to detachably lock theupper end of the fuseholder 66 in position. U- bolt 79 is covered byinsulating means 83 such as a coating of epoxy resin or a sleeve ofinsulating material. Spring 80 is constructed from a long rod bentsymmetrically about its midpoint to have an approximate U-shape with twolegs 84 which are bent to form loops 85, and the free ends of the spring80 are inserted through apertures (not shown) in hood 77. The legs 84 ofthe spring 80 are kinked laterally in opposite directions to define awidened mouth (not shown) having converging sides which function toalign the upper end of fuseholder 66 as it is swung to closed positionby a hookstick engaging the eye 75. Hood 77 carries an eyebolt connector86 which constitutes the line terminal for the combined fuse andarrester and is adapted to be connected to a power line conductor 87.

A split-sleeve 83 clamped to the lower end of dropout fuse tube 68 hasradial extending arms 89 secured by means such as rivets to a U-shapedsupport member 90 embracing the arms 89 and having a hookstick receivingeye 92 for removing and re-positioning the fuse holder in the usualmanner. A fuse link extracting lever, or flipout lever, 93 is pivoted bya pin 94 to the support member 90. The fuse link extracting lever 93 isprovided with trunnions 96 and also with a threaded member 97 forclamping the lower end of the flexible fuse link 69 to the extractinglever 93.

The bottom contact 61 includes a metallic member 98 fastened to thelower end of insulating member 10 by a U-bolt 99. Member 98 is providedwith a pair of arms 100 having hook-like portions 102 which receive thetrunnions 96. The diameter of the trunnions 96 is greater than thespacing between the arms 100 and the end of the hook-like portions 102,and the trunnions 96 are approximately semicircular, i.e., flat on oneside, to permit insertion and removal of the trunnions 96 within thehooklike portions 102 from one direction only and to prevent removalthereof until the fuse tube 68 is pivoted approximately 180 degrees fromits normally latched position shown in the drawing. Consequently, therecoil forces resulting from operation of fuse link 69 and expulsion ofgases from fuse tube 68 will be transmitted directly to hanger 11through the directly-engaged trunnions 96 and hook-like portions 102.

The fuse link extracting lever 93 is normally held from pivoting by thetensioned fuse link 69. A metallic terminal mounting strap 105 aflixedto lower contact member 98 carries the eyebolt connector 62 which isconnected to the wire 63 leading to the load.

Means including a pair of spaced apart electrodes are connected betweenthe intermediate contact 65 and the upper terminal 57 for providing apath to ground through the lightning arrester assembly 18 and hanger 11for impulse and surge voltages appearing on power line 87 and forpreventing continued flow of follow current through the lightningarrester assembly 18 in the event of damage to the lightning arrestorassembly. In the preferred embodiment shown in FIGS. 1 and 2 such meansconstitute the spaced apart upper and lower electrodes 113 and 114,respectively, of an isolator 115 of the type disclosed in US. 2,860,210to Stoelting et a1. having the same assignce as this application. Thespaced apart electrodes 113 and 114 are enclosed in a breakableweatherproof housing 116, and an explosive shell 117 disposed in thebore of the pper electrode 113 is arranged to explode and break thehousing 116 in the event of excessive flow of follow current betweenelectrodes 113 and 114. Isolator 115 is carried between a rigid,laterally extendin arm 118 on the body portion of the eyebolt connector86 for the power line conductor 87 and the flexible connecting strap 58of the upper terminal 57. Surge voltages normally break down the air gapbetween electrodes 113 and 114, the surge voltage and follow currentflow across such air gap without exploding the shell 117, and the followcurrent is limited by the valve material 19 and interrupted by the sparkgap means of the lightning arrester 18. In the event of damage to thelightning arrester 18 from an extreme lightning stroke or other causes,the arrestor acts as a short circuit and follow current continues toflow through the arrester 18 until the heat generated thereby explodesthe shell 117 and separates the electrodes 113 and 114 to electricallydisconnect the lightning arrester 18 from the power line wire 87.

Means are provided in the preferred embodiment of FIGS. 1 and 2 toincrease the stray capacitance of the baffle plate electrodes of thespark gap means 20 to ground and thus render the voltage distributionacross the spark gap means more uniform and stabilize the sparkoverpotential of the spark gap means. The spark gap means 20 should not bepositioned at the upper end of tubular portion 17 since with sucharrangement the full line-to-ground potential would be impressed acrossthe tubular porcelain wall and a high level of corona could result. Thestray capacitance of the intermediate contact 65, including hood 77which is at power line potential, to the baffle plate electrodes 25increases the leakage current between bafiie plate electrodes andaccentuates the non-uniformity of the potential distribution across thespark gap means. A U-shaped, silicon bronze grading strap 130 isprovided at the lower end of spark gap means 20 to increase the straycapacitance between the baffle plate electrodes 25 and the groundedhanger 11. Such increase in stray capacitance to grounded hanger 11increases the leakage current between electrodes 25, makes the potentialdistribution across the spark gap means 20 more uniform, and stabilizesthe flashover potential of the spark gap means 20. The cross-piece ofthe U-shaped strap 130 is positioned between the inverted cup-shapedmember 34 and the metal disk 38. The upwardly extending arms 131 ofstrap 130 are disposed between the spark gap means 20 and the innersurface of tubular portion 17. The ends of the upwardly extending arms131 are covered with insulation 132 to reduce corona between theintermediate contact 65, which is at the potential of the power line 87,and the arms 131 of the grading strap 130 which are at ground potential.

The electrodes 113 and 114 of the isolator 115 may be bridged by meanssuch as an annular resistor 133 of negative resistance material forpreventing accumulation of charge on the upper electrode 113, therebyeliminating radio interference which might result from such accumulationof charge. The annular resistor 133 is disposed against the upperelectrode 113 and is electrically connected to the lower electrode 114by means of a metallic spring spider 134.

In the embodiment of FIG. 3, the means for providing a path to groundthrough the lightning arrester 18 and for preventing continued flow offollow current through the arrester in the event of damage to thearrester comprises fixed spark gap means defined by an upwardlyextending electrode 120 integral with the eyebolt connector 86 for thepower line conductor 87 and an L-shaped strap electrode 58' mounted onstud 57 of the upper terminal so as to be spaced from electrode 120 anddefine a fixed air gap therebetween. In the event of damage to thelightning arrestor of this embodiment, the spark gap between electrodes58' and 120 will continue to flash over as a result of lightningstriking the power line, and follow current will continue to flow toground through the damaged 6 lightning arrester until a back-up devicesuch as recloser in the power line 87 interrupts the flow of current inthe power line. When power is restored to the line 87, the spark gapbetween electrodes 58' and will isolate the lightning arrester 18 fromthe power line and prevent the flow of sixty-cycle current through thedamaged arrester.

The spark gap 20 means of the embodiment of FIG. 3

has an annular ceramic spacer 122 of resistance material disposed ineach spark gap between an upper cup-shaped electrode 123 and a similarlower electrode 124 of inverted cup-shape. The resistance spacers 122form a voltage divider which maintains uniform voltage distributionacross the spark gaps of the arrester. The bottom contact 61, theintermediate contact 65 including hood 77 and spring 80, the fuse tube68 as well as the electrodes such as 58' and 120 defining the spark gapexternal to the lightning arrester are disposed on a side of theinsulating member 10 diametrically opposed to the side from which themetallic hanger 11 protrudes. Since cap 50 and U-bolt 79 are coveredwith insulating material 53 and 83 respectively, no electricallyenergized metallic parts are exposed on the side of the insulatingmember 10 from which the grounded hanger 11 protrudes. Consequently,birds or animals sitting on the grounded hanger 11 do not have readyaccess to metal parts at the potential of the line. Similarly, a bird oranimal sitting on the bottom or intermediate contact 61 or 65 cannoteasily contact a grounded metallic part since it would have to reacharound to the opposite side of the insulating member 10 in order to doso. Consequently, continuity of customer service is assured and falseoutages, which could result from animals short circuiting betweenmetallic parts at different electric potentials, are prevented.

It will also be appreciated that the disclosed combined arrester andfuse cutout saves considerable mounting space on the pole, crossarm ortransformer casing and also provides considerable saving in theinstallation expense in comparison to separate arrester and fuse cutout.

The recoil forces resulting from operation of fuse link 69 and expulsionof gases from fuse tube 68 are transmitted to the hanger 11 through ahigh strength portion of insulating member 10 between hanger 11 andbottom contact 61 which may be solid in cross section and thusconsiderably stronger than the tubular porcelain members of prior artdevices. In the production model a small diameter axial bore is providedin the lower portion of insulating member 10 between hanger 11 and thebottom surface thereof to facilitate molding the porcelain, but thislower diameter portion is of substantially greater strength than thetubular upper portion 17. High cantilever forces, which were applied tothe base mounting of prior art combined arrester and cutouts when thefuse cutout was closed, are eliminated with the disclosed construction.

The combined fuse tube cutout and arrester has higher interruptingcapacity than prior art devices utilizing open fuse links, for example,its interrupting rating is 10,000 R.M.S. asymmetrical amperes. Thecombined cutout and arrester provides complete cutout and lightningarrester protection on transformers, capacitor racks and banks, atsectiona lizing points, or at small substations and switchmg stations.

While only a few embodiments of the invention have been illustrated anddescribed, many modifications and variations thereof Will be apparent tothose skilled in the art, and consequently, it is intended to cover inthe appended claims all such modifications and variations which fallwithin the true spirit and scope of the invention.

What I claim as new and desire to secure by Letters Patent of the UnitedStates is:

1. A combined fuse cutuout and lightning arrester comprising, incombination, elongated insulating means having an upper terminal, abottom contact, and a contact intermediate said upper terminal and saidbottom 4 contact adapted to be connected to a power line, a fuseholderpivotally mounted on said bottom contact and latched in contact withsaid intermediate contact, a metallic mounting member affixed to saidinsulating means between said intermediate and bottom contacts andadapted to be connected to ground, the upper portion of said insulatingmeans being hollow, a lightning arrestor assembly within said hollowupper portion of said insulating means including spark gap means andvalve material connected in series relation between said upper terminaland said metallic mounting member, and means including a pair of spacedapart electrodes exterior of said insulating means one of which isconnected to said upper terminal and the other of which is connected tosaid intermediate contact for providing a path through said lightningarrester assembly to ground for impulse voltages on said line and forisolating said arrester assembly from said line and from saidintermediate contact to prevent the fiow of follow current through saidarrester assembly in the event of damage to said arrester assembly.

2. In the combination defined in claim 1 wherein said spaced apartelectrodes define a fixed spark gap which isolates said lightningarrester assembly in the event of damage to said arrester assembly aftera back-up device opens said power line and interrupts the flow of followcurrent through said damaged arrester assembly.

3. In the combination defined by claim 1 wherein an explosive charge isarranged to separate said electrodes in the event of excessive flow ofcurrent between said electrodes.

4. A combined fuse cutout and lightning arrester comprising, incombination, elongated insulating means having an upper terminal, abottom contact adapted to be connected to the load, and a contactintermediate said upper terminal and said bottom contact adapted to beconnected to a line; an expulsion fuseholder pivotally mounted on saidbottom contact and latched in contact with said intermediate contact, ametallic mounting member affixed to said insulating means between saidintermediate and bottom contacts and adapted to be connected to ground,the upper portion of said insulating means being hollow and the portionof said insulating means between said mounting member and said bottomcontact being of greater section modulus than said hollow upper portion,whereby the portion of said insulating means transmitting the recoilforces incident to operation of said expulsion fuseholder to saidmounting mem ber is of high strength, a lightning arrester assemblyincluding valve material in electrical series relation with spark gapmeans disposed within said hollow upper portion of said insulating meansand electrically connected between said upper terminal and said metallicmounting member, and means including a pair of spaced apart electrodesexterior of said insulating means one of which is connected to saidupper terminal and the other of which is connected to said intermediatecontact for providing a path to ground through said arrester assemblyfor impulse voltages on said line and for isolating said arresterassembly from said intermediate contact and said line in the event saidarrester assembly is damaged.

5. A combined lightning arrester and fuse cutout comprising, incombination, an elongated insulating member having a tubular upperportion, an upper terminal, a bottom contact adapted to be connected toa load, and a contact intermediate said upper terminal and said bottomcontact adapted to be connected to a power line; a fuseholder pivotallymounted on said bottom contact and latched in contact with saidintermediate contact, a metallic hanger member affixed to saidinsulating member between said intermediate and bottom contacts andcommunicating with the interior of said tubular upper portion, alightning arrester assembly within said tubular upper portion includingvalve elements adjacent said upper terminal and spark gap means adjacentthe portion of said metallic hanger member within said tubular portionand being connected in series with said valve elements between saidupper terminal and said hanger member, said spark gap means including aplurality of spaced apart metallic electrodes defining a plurality ofspark gaps in series, metallic means between said electrodes and saidhanger member for increasing the stray capacitance of said electrodes tosaid hanger member, whereby the potential distribution in said spark gapmeans is made more uniform and the sparkover potential of said spark gapmeans is stabilized, and means including a pair of spaced apartelectrodes exterior of said insulating member one of which is connectedto said upper terminal and the other of which is connected to saidintermediate contact for providing a path to ground through saidarrester assembly for impulse voltages on said line and for isolatingsaid arrester assembly from said intermediate contact and said powerline in the event of damage to said arrester assembly.

6. A combined fuse cutout and lightning arrester comprising, incombination, elongated insulating means having an upper terminal, abottom contact adapted to be connected to a load and a contactintermediate said upper terminal and said bottom contact adapted to beconnected to a line; means for affixing said intermediate and bottomcontacts on one side of said insulating means, a fuseholder pivotallymounted on said bottom contact and disposed on said one side of saidinsulating means and being latched in contact with said intermediatecontact, a metallic mounting member affixed to said insulating meansbetween said intermediate and bottom contacts on a side of saidinsulating means diametrically opposed to said one side and beingadapted to be connected to ground, the upper portion of said insulatingmeans being hollow, a lightning arrester assembly within said hollowupper portion including spark gap means and valve material connected inseries relation between said upper terminal and said metallic mountingmember, and means including a pair of spaced apart electrodes exteriorof said insulating means disposed on said one side of said insulatingmeans one of which is connected to said upper terminal and the other ofwhich is connected to said intermediate contact for providing a path toground through said arrester assembly for impulse voltages on said lineand for isolating said arrester assembly from said line and saidintermediate contact in the event of damage to said arrester assembly,said grounded mounting member being the only metallic part protrudingfrom said diametrically opposed side of said insulating means, wherebybirds and animals resting on said mounting member and said bottom andintermediate contacts do not have ready access to a metallic part at adifferent electric potential and cannot easily cause a short circuit.

7. A combined fuse cutout and lightning arrester comprising, incombination, elongated insulating means having an upper terminal, abottom contact adapted to be connected to a load, and a contactintermediate said upper terminal and said bottom contact adapted to beconnected to a power line; an expulsion fuseholder, a lightning arresterassembly comprising valve elements and spark gap means in electricalseries relation, said fuseholder and said arrester assembly being ofapproximately the same length and being substantially shorter than saidinsulating means, said fuseholder being pivotally mounted on said bottomcontact and latched in contact with said intermediate contact, ametallic terminal afiixed to said insulating means between saidintermediate and bottom contacts and adapted to be connected to ground,the upper portion of said insulating means being tubular, said lightningarrester assembly being positioned within said tubular upper portion andconnected electrically between said metallic terminal and said upperterminal, and means including a pair of spaced apart electrodes exteriorof said insulating means one of which is connected to said upperterminal and the other of which is connected to 9 said intermediatecontact for providing a path through said arrester assembly to groundfor surge voltages on said line and for isolating said arrester assemblyfrom said line and from said intermediate contact to prevent flow offollow current through said arrester assembly in the event of damage tosaid arrester assembly.

8. In a protective device, the combination of an insulating memberhaving an axial bore, a lightning arrester including valve material andspark gap means in serial relation within said bore, said spark gapmeans within said bore including a plurality of spaced apart electrodesdefining a plurality of serially connected spark gaps, a metalliccontact on the exterior of said insulating member adapted to beconnected to a power line, a metallic terminal on the exterior of saidinsulating member adapted to be connected to ground, the potentialdistribution across said spaced apart electrodes being non-uniform andthe leakage currents through the stray capacitance between said metalliccontact and said spark gap means intensifying said non-uniformity anddecreasing the sparkover potential of said spark gap means, and metallicmeans disposed between said metallic terminal and said spark gap meansfor increasing the stray capacitance between said metallic terminal andsaid spark gap electrodes, whereby said lastnamed means stabilizes thesparkover potential of said spark gap means.

9. A combined fuse cutout and lightning arrester comprising, incombination, elongated upright insulating means including upper andlower cylindrical insulator portions joined in axial alignment, raisedcircumferential petticoats on each of said insulator portions, ametallic terminal affixed to said insulating means adjacent the junctionof said upper and lower insulator portions and adapted to be connectedto ground, a bottom contact on the lower end of said lower insulatorportion adapted to be connetced to a load, said upper insulator portionbeing hollow, an upper terminal adjacent the upper end of said upperinsulator portion, a lightning arrester assembly within said hollowupper insulator portion including spark gap means and valve materialconnected in series relation between said upper terminal and saidmetallic terminal, an intermediate contact on said upper insulatorportion between said metallic terminal and said upper terminal andadapted to be connected to a power line, an explusion fuseholderpivotally mounted on said bottom contact and latched in contact withsaid intermediate contact, and a pair of spaced apart electrodes one ofwhich is connected to said upper terminal and the other of which isconnected to said intermediate contact.

10. A combined fuse cutout and lightning arrester comprising, incombination, elongated upright insulating means having upper and lowercylindrical insulator portions joined in axial alignment, a metallicterminal aflixed to said insulating means adjacent the junction of saidupper and lower insulator portions and adapted to be connected toground, a first contact on said lower insulator portion spaced belowsaid metallic terminal and adapted to be connected to an electricalload, a second contact on said upper insulator portion spaced above saidmetallic terminal and adapted to be connected to a power line, anexpulsion fuseholder pivotally mounted on said first contact andreleasably latched in contact with said second contact, said upperinsulator portion being hollow, and a lightning arrester including sparkgap means and valve material disposed in said hollow upper insulatorportion and connected in electrical series relation between said secondcontact and said metallic terminal.

11. A combined fuse cutout and lightning arrester comprising, =incombination, elongated upright insulating means having an axialcompartment in the upper end thereof, a metallic terminal affixed tosaid elongated insulating means intermediate its ends and extending fromone side of said insulating means and adapted to be connected to ground,a first metallic contact affixed to said 10 insulating means adjacentthe lower end thereof in spaced relation below said terminal andextending from the side of said insulating means opposite to saidterminal and adapted to be connected to a load, a second metalliccontact affixed to said insulating means in spaced relation above saidterminal and extending from the same side of said insulating means assaid first contact and adapted to be connected to a power line, -anexpulsion fuseholder pivotally mounted on said first contact andreleasably latched in engagement with said second contact, whereby birdsand animals touching metallic parts do not have ready access to metallicparts at a different electric potential and connot easily cause a shortcircuit, and a lightning arrester including negative resistance valvematerial within said axial compartment and a plurality of spaced apartelectrodes defining a plurality of spark gaps within said axialcompartment connected in series with said valve material between saidsecond contact and said terminal.

12. A combined fuse cutout and lightning arrester comprising, incombination, elongated upright insulating means having upper and lowercylindrical insulator portions joined in axial alignment, a metallicmounting member affixed to said insulating means adjacent the junctionof said upper and lower insulator portions, a bottom contact on saidlower insulator portion spaced below said mounting member and adapted tobe connected to an electrical load, said upper insulator portion havingan axial compartment therein and being open at its upper end, alightning arrester including spark gap means and valve material disposedwithin said axial compartment, means for closing said open end of saidupper insulator portion and for sealing said axial compartment havingsaid valve material and spark gap means therein from the atmosphere, anintermediate contact on said upper insulator portion above said mountingmember adapted to be connected to a power line, an expulsion fuseholderpivotally mounted on said bottom contact and releasably latched inengagement with said intermediate contact, said lower insulator portionbeing of greater section modulus than said upper insulator portion,whereby recoil forces incident to operation of said expulsion fuseholderare transmitted to said mounting member through the higher strengthportion of said elongated insulating means, and an upper terminal onsaid closing means connected in a series circuit with said valvematerial and said spark gap means between said intermediate contact andsaid mounting member.

13. A combined fuse cutout and lightning arrester comprising, incombination, elongated upright insulating means including upper andlower cylindrical insulator portions joined in axial alignment, ametallic mounting member afiixed to said insulating means adjacent thejunction of said upper and lower insulator portions and adapted to beconnected to ground, a bottom contact on said lower insulator portionbeneath said mounting member and adapted to be connected to anelectrical load, said upper insulator portion being hollow, an upperterminal adjacent the upper end of said upper insulator portion, anintermediate contact on said upper insulator portion between saidmetallic mounting member and said upper terminal and adapted to beconnected to a power line, an expulsion fuseholder pivotally mounted onsaid bottom contact and adapted to be releasably latched in engagementwith said intermediate contact, and a lightning arrester including sparkgap means and valve material with in said hollow upper insulator portionand said spark gap means and said valve material being connected in aseries circuit with said upper terminal between said intermediatecontact and said mounting member.

14. A combined fuse cutout and lightning arrester comprising, incombination, elongated upright insulating means having an axialcompartment in the upper end thereof and being open at its upper end, ametallic mounting member affixed to said elongated insulating means 11intermediate its ends and adapted to be connected to ground, a firstcontact afliXed to said insulating means below said mounting member andadapted to be connected to ground and having bearing portions and beingadapted to be connected to an electrical load, an expulsion fuseholderpivotally mounted in said bearing portions, a second contact affixed tosaid insulating means above said mounting member and having means toreleasably latch said fuseholder and being adapted to be connected to apower line, lightning arrester means including valve material and aplurality of spaced electrodes defining a plurality of spark gapspositioned within said axial compartment, means for closing the openupper end of said elongated insulating means and for sealing said axialcompartment having said valve material and said electrodes therein fromthe atmosphere, said lastnamed means having terminal means extendingtherethrough connected in series with said valve material and said sparkgaps between said second contact and said mounting member.

References Cited by the Examiner SAMUEL BERNSTEIN, Primary Examiner.

1. A COMBINED FUSE CUTOUT AND LIGHTING ARRESTER COMPRISING, INCOMBINATION, ELONGATED INSULATING MEANS HAVING AN UPPER TERMINAL, ABOTTOM CONTACT, AND A CONTACT INTERMEDIATE SAID UPPER TERMINAL AND SAIDBOTTOM CONTACT ADAPTED TO BE CONNECTED TO A POWER LINE, A FUSEHOLDERPIVOTALLY MOUNTED ON SAID BOTTOM CONTACT AND LATCHED IN CONTACT WITHSAID INTERMEDIATE CONTACT, A METALLIC MOUNTING MEMBER AFFIXED TO SAIDINSULATING MEANS BETWEEN SAID INTERMEDIATE AND BOTTOM CONTACTS ANDADAPTED TO BE CONNECTED TO GROUND, THE UPPER PORTION OF SAID INSULATINGMEANS BEING HOLLOW, A LIGHTNING ARRESTOR ASSEMBLY WITHIN SAID HOLLOWUPPER PORTION OF SAID INSULATING MEANS INCLUDING SPARK GAP MEANS ANDVALVE MATERIAL CONNECTED IN SERIES RELATION BETWEEN SAID UPPER TERMINALAND SAID METALLIC MOUNTING MEMBER, AND MEANS INCLUDING A PAIR OF SPACEDAPART ELECTRODES EXTERIOR OF SAID INSULATING MEANS ONE OF WHICH ISCONNECTED TO SAID UPPER TERMINAL AND THE OTHER OF WHICH IS CONNECTED TOSAID INTERMEDIATE CONTACT FOR PROVIDING A PATH THROUGH SAID LIGHTNINGARRESTER ASSEMBLY TO GROUND FOR IMPULSE VOLTAGES ON SAID LINE AND FORISOLATING SAID ARRESTER ASSEMBLY FROM SAID LINE AND FROM SAIDINTERMEDIATE CONTACT TO PREVENT THE FLOW OF FOLLOW CURRENT THROUGH SAIDARRESTER ASSEMBLY IN THE EVENT OF THE DAMAGE TO SAID ARRESTER ASSEMBLY.